Axial flow fan assembly

ABSTRACT

An axial flow fan assembly wherein the ring in which the fan rotates comprises a cylindrical body having a box-shaped stiffening ring about its outer circumference.

nited States Patent 1191 Shipes 1 Aug. 6, 1974 [5 AXIAL FLOW FAN ASSEMBLY 2,001,315 5/1935 Proctor et a1 138/159 2,164,660 7/1939 Miller 220/71 [75] Inventor- Kelly Houston 2,910,322 10/1959 Magor 220/71 [73] Assignee: Hudson Products Corporation, 3,302,547 2/1967 wasserfnanm" 98/43 R Houston, Tex. 3,714,970 2/1973 Kunsagi 138/172 [22] Filed, M ay 29 1973 FOREIGN PATENTS OR APPLICATIONS 533,560 2/1941 Great Britain 98/39 [21] App]. No.: 364,951

Primary Examiner-Carlton R. Croyle 52 U.S. c1 415/219, 415/182, 138/172, Assistant Examiner-Louis Casaregolfl 220/71 Attorney, Agent, or Firm-W. F. Hyer; Marvin B. 51 Int. Cl. F01d 2s/24,1=01d 25/26 Elckemoht [58] Field of Search 415/174, 217, 219; 41 6/93,

416/94; 138/159, 161, 172; 29/157 R; ABSTRACT 113/1 16 A, 116 UT; 98/39, 43 R; 220/71, 5 An axial flow fan assembly wherein the ring in which the fan rotates comprises a cylindrical body having a [56] References Cited box-shaped stiffening ring about its outer circumfer- UNITED STATES PATENTS ence- 837,476 12/1906 Keiner 220/71 6 Claims, 6 Drawing Figures I AXIAL FLOW FAN ASSEMBLY This invention relates to an axial flow fan assembly of the type especially adapted for use as part of an air cooler in process and power plants or other industrial environments. More particularly, it relates to a fan assembly of this type having an improved fan ring in which the fan rotates.

Since fan assemblies of this type may be quite large, ranging in diameter from six to thirty feet, they create considerable air turbulence. This, in turn, creates much vibration in the fan as well as in the fan ring, and, as a result, causes considerable wear and tear on the fan assembly and the parts of the air cooler or other equipment to which the fan assembly is connected. The vibration also raises the noise level generated by the fan assembly, and thus creates a problem in keeping with tolerable noise level standards.

Conventional rings for fan assemblies of this type are galvanized, which causes them to warp and thus to lose their shape desired for fitting closely about the fan. The rings may also be forced out of shape during handling. Also, even when extreme care is taken to maintain their shapes, the rings may be found to exceed allowable tolerances when assembled about the fan. In order to compensate for these tolerance problems, and thus increase the efficiency of the fan assembly, it has been proposed to line the ring with a material which will conform to the outer diameter of the fan. However, this is an expensive procedure, and, in some cases, will actually raise the noise level of the fan assembly.

An object of this invention is to provide an axial flow fan assembly in which such vibration and noise level are minimized.

Another object is to provide such a fan assembly in which tolerances between the ring and the fan may be maintained close enough to eliminate the tip seal and thus further reduce noise levels.

Still another object is to provide such a fan assembly having a ring of such construction that its desired shape may be maintained not only during manufacture and handling, but also during assembly with the fan.

Yet another object is to provide such a fan assembly having a ring which is stiffened so as to maintain its shape ina simple and inexpensive manner.

These and other objects are accomplished, in accordance with the illustrated embodiment of the invention,

by an axial flow fan assembly having a fan ring comprising a hollow cylindrical body and box-shaped rib means extending about a substantial portion of the outer circumference of the body. The ring is formed of a plurality of curved segments, preferably four identical quadrants, adapted to be connected to one another at their side edges. More particularly, the segments comprise curved sheets having flanges which may be bolted to one another with one or more shims disposed therebetween, thereby permitting adjustment for out-of-round in the inner circumference of the ring during assembly of the ring. Each box-shaped rib comprises a channel having its inner edges curved about the outer side of each body segment. In accordance with the preferred and illustrated embodiment of the invention, the channel is formed of a flat sheet which is slotted along its opposite sides, so that, when folded into a channel shape along lines transverse to the slots, it may be bent into a shape corresponding to the outer side of the segment. When the channel is disposed about the outer side of the segment, its inner edges are welded to the segment intermediate the slots. The ends of the channels forming the ribs are spaced from the flanges on each side edge of each body segment, so as to provide access to nuts and bolts for connecting the flanges together.

In the drawings, wherein like reference characters are used throughout to designate like parts:

FIG. 1 is an elevational view of an air cooler wherein an axial flow fan assembly constructed in accordance with the present invention is mounted above a tube bundle, the air cooler being broken away in part to show both the fan assembly and a portion of the air cooler;

FIG. 2 is a top view of the fan assembly, as seen along broken lines 2-2 of FIG. 1;

FIG. 3 is an enlarged vertical sectional view of a portion of the fan ring of the fan assembly, as seen along broken line 33 of FIG. 4;

FIG. 4 is a horizontal cross-sectional view of a portion ofthe fan ring, as seen along broken lines 44 of FIG. 3;

FIG. 5 is a plan view of a sheet adapted to be formed into a channel-shaped rib; and

FIG. 6 is a view of the sheet of FIG. 5 after slots have been formed in its side edges, and showing in broken lines the locations at which the sheet is to be bent transversely to the direction of the slots.

With reference now to the above-described drawings, the air cooler shown in FIG. 1, and designated in its entirety by reference character 10, includes a tube bundle 11 mounted on vertical columns 12, and an axial flow fan assembly 13 mounted above the tube bundle by means of a transition 14. As shown by the broken-away portion of FIG. 1, the bundle 11 includes a plurality of heat exchange tubes 15 extending laterally between headers (not shown) at opposite ends of the bundle for conducting a process fluid to be cooled across the air stream caused by the fan assembly 13. Side walls 16 extend along opposite sides of the bundle to confine air flow to the bundle.

The fan assembly 13 includes a cylindrical fan ring 17 having a fan 18 mounted therein for rotation about the axis of the ring. More particularly, and as shown in the drawings, the tips of the blades of the fan move closely and concentrically within the fan ring so as to provide the fan assembly with maximum efficiency.

The fan 18 is mounted on a shaft 19 which extends vertically and coaxially of the fan ring. The lower end of the shaft is driven by a motor 20 suspended from the tube bundle or other portion of the air cooler in any suitable manner. The motor in turn drives a belt within a belt guard 21 disposed about the lower end of the shaft for rotating the fan at a desired speed. The shaft is mounted for rotation at its upper end by means of a bearing 22 supported in a lower extension 23 of the fan ring by means of radial struts 22b. Each fan 13 includes a hub 24 fixed to the shaft and having a plurality of sockets 25 extending radially from the hub. The individual blades 26 of the fan are adjustably mounted within the sockets 25.

As best shown in FIG. 2, the fan ring 17 includes a hollow cylindrical body 27 made up of four segments comprising identical quadrants 27A, 27B, 27C and 27D. Thus, each segment is curved about approximately so that, when the segments are connected at their opposite end edges, as shown in FIG. 2, they form the cylindrical body of the fan ring.

As shown in FIG. 4, each segment comprises a curved metal sheet 28 having flanges 29 extending radially outwardly at its opposite end edges. The flanges are provided with holes to receive bolts 30 for connecting the flanges and thus the body segments together. As also shown in FIG. 4, one or more shims 31 may be disposed between the flanges and provided with holes to receive the bolts 30.

An outwardly extending flange 32 is provided at the upper end and an outwardly extending flange 33 is provided at the lower end of the curved sheet 28, as best shown in FIG. 3. The upper flange 32 not only stiffens the upper end of the segment, but also provides a means by which a fan ring of another fan assembly may be stacked above it. As best shown in FIG. 3, the lower flange 33 is connected to a flange 34 on the upper end of the extension 23 by bolts 35 and thus provides a means for mounting the fan ring above the transition 14 of the air cooler. Alternatively, the lower flange 33 may, like the flange 32, supply the means by which fan rings may be mounted one above the other.

As previously described, each fan ring body is stiffened by means of a box-shaped rib 36 extending about a substantial portion thereof. Thus, when the segments are assembled into a complete fan ring 17, as shown in FIG. 2, the ribs extend substantially about the entire outer circumference of the body of the fan ring. As shown, and as previously described, each rib comprises a channel which is curved to extend about the outer side of the sheet 28. More particularly, and as shown in FIG. 1, the channel extends about and spans the tip of the blades of the fan 18.

As illustrated in FIGS. and 6, each rib 36 is preferably formed from a flat metal sheet 37 having slots 38 formed in each side edge in generally equally spacedapart relation and aligned with the slots along the opposite edge. As will be understood from the description to follow, the number and spacing of the slots will depend upon the radius of the fan ring, and thus the degree to which the slotted edges of the sheet must be bent.

In any event, upon forming of the slots, the sheet is bent along vertical lines transverse to the direction of the slots, as indicated at 39 and 40 in FIG. 6. More particularly, portions of the sheet between the broken lines and the side edges thereof are bent to approximately a right angle with respect to the central portion or web 41 of the sheet so that, when the channel is bent and extended about the outer side of the sheet 28, it forms a box-shaped rib.

The thusly formed channel is bent into a shape for fitting about the outer side of the sheet 28 in any suitable manner, the bending being made possible by the weakened edges of the sheets where they are slotted. When the channel has been so bent, it is moved to the desired position about the outer side of the sheet 28 and welded thereto, along its edges between adjacent slots 38, as indicated at 42.

As best shown in FIG. 4, the channel 36 is of lesser circumferential extent than the body segment, so that its opposite ends are spaced from the outwardly extending flanges 29. This not only facilitates bolting of the flanges of adjacent segments to one another, but also reduces the cost of fabricating the fan ring in that it avoids the necessity of cutting the inner edges of the channel for fitting over the portion of the flange 29 secured to the outer side of the sheet 28.

In the manufacture of the fan ring, the channel 36 is welded to the ring body prior to galvanizing, so that the stiffening of the thusly formed ring segment reduces to a minimum the warpage resulting from galvanizing. This stiffening of the fan ring segments also renders them more resistant to changes in shape resulting from handling. Consequently, when assembled, the overall ring is usually found to be sufficiently close to round to avoid the necessity of providing tip seals about its inner circumference. Furthermore, any out of roundness of the ring may be further compensated for upon assembly of the quadrants. Thus, as previously described, one or more shims 31 may be selectively disposed between the flanges 29 as the quadrants are bolted together.

From the foregoing it will be seen that this invention is one well adapted to attain all of the ends and objects hereinabove set forth, together with other advantages which are obvious and which are inherent to the apparatus.

It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the claims.

As many possible embodiments may be made of the invention without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

The invention having been described, what is claimed is:

1. An axial flow fan assembly, comprising a ring having a plurality of curved segments adapted to be connected to one another to form a hollow cylindrical body, a box-shaped rib extending about a substantial portion of the outer side of each body segment intermediate its opposite ends, and a fan mounted within the body for rotation about the axis of the body, each rib comprising a channel having its inner edges curved about the outer side of the body segment, and each channel being formed of a flat sheet which is slotted along its opposite sides, so that, when folded into a channel shape along lines transverse to the slots, it may be bent into a shape corresponding to the outer side of the body segment.

2. An axial flow fan assembly, comprising a ring including a hollow cylindrical body, box-shaped rib means extending about a substantial portion of the outer side of the body, and a fan mounted within the body for rotation about the axis of the body, said rib means comprising channel means having its inner edges curved about the outer side of the body, and said channel means being formed of flat sheet means which is slotted along its opposite sides, so that, when folded into a channel shape along lines transverse to the slots, it may be bent into a shape corresponding to the outer side of the body.

3. An assembly of the character defined in claim 1, wherein the inner edges of the channel are welded to the body segment intermediate the slots.

4. An assembly of the character defined in claim 1, wherein each body segment comprises a curved sheet having flanges along its side edges for connection to flanges along the side edges of the curved sheet of adjacent segments.

5. An assembly of the character defined in claim 4, wherein the ends of the ribs are spaced from the flanges to permit access to bolts for connecting the flanges of adjacent segments.

6. An assembly of the character defined in claim 2, wherein the inner edges of the channel means are welded to the body intermediate the slots. 

1. An axial flow fan assembly, comprising a ring having a plurality of curved segments adapted to be connected to one another to form a hollow cylindrical body, a box-shaped rib extending about a substantial portion of the outer side of each body segment intermediate its opposite ends, and a fan mounted within the body for rotation about the axis of the body, each rib comprising a channel having its inner edges curved about the outer side of the body segment, and each channel being formed of a flat sheet which is slotted along its opposite sides, so that, when folded into a channel shape along lines transverse to the slots, it may be bent into a shape corresponding to the outer side of the body segment.
 2. An axial flow fan assembly, comprising a ring including a hollow cylindrical body, box-shaped rib means extending about a substantial portion of the outer side of the body, and a fan mounted within the body for rotation about the axis of the body, said rib means comprising channel means having its inner edges curved about the outer side of the body, and said channel means being formed of flat sheet means which is slotted along its opposite sides, so that, when folded into a channel shape along lines transverse to the slots, it may be bent into a shape corresponding to the outer side of the body.
 3. An assembly of the character defined in claim 1, wherein the inner edges of the channel are welded to the body segment intermediate the slots.
 4. An assembly of the character defined in claim 1, wherein each body segment comprises a curved sheet having flanges along its side edges for connection to flanges along the side edges of the curved sheet of adjacent segments.
 5. An assembly of the character defined in claim 4, wherein the ends of the ribs are spaced from the flanges to permit access to bolts for connecting the flanges of adjacent segments.
 6. An assembly of the character defined in claim 2, wherein the inner edges of the channel means are welded to the body intermediate the slots. 